Apparatus for the stringing of tennis rackets



531211.28, 11936. J H PROCTOR 2,028,804

APPARATUS FOR THE STRINGING OF TENNIS RACKETS Original Filed June 22, 1932 Jar ma 771;: %mu/ 7% w fiaafat,

Patented Jan. 28, 1936 PATENT OFFICE APPARATUS FOR THE STRINGING OF TENNIS RACKETS James Hutton Proctor, Northbridge, New South Wales, Australia, assignor to Ace Racket stringers (Foreign Ri ghts) Limited, Sydney,

New South Wales, Australia, a company of New South Wales Original application 618,746. Divided an 28, 1934, Serial No. '7 Zealand, and Great 1 Claim.

This invention consists in apparatus for stringing tennis rackets.

In the practice of the trade the longitudinal string is first drawn through the holes in the racket frame, starting from the central strings and working outwards; the. frame is then strutted longitudinally to prevent distortion and the string lengths are then separately tautened up and tensioned successively; as each length is drawn taut by the workman it is checked by pushing an awl wedge into the outgoing hole in the frame so as to jamb it, and it is then twanged, the sonorous note emitted being the indicator relied on by the workman for ascertaining the degree of tension.

After the mains or longitudinal strings are thus tensioned and secured, the cross strings are similarly drawn through the appropriate holes in the frame, and like the longitudinal strings are then tautened, tensioned, and secured.

Continuous strings for the longitudinal courses and for the transverse courses are used in my stringing method which follows conventional practice insofar as the insertion and awling of the strings is concerned, each separate string length in the lattice being separately tensioned.

As each course of string is tensioned it is checked temporarily at the outgoing frame hole by means of a wedge-awl and the next course of the string is then drawn taut and tensioned and similarly checked, and so on for all the longitudinal and transverse string courses successively until the frame is fully strung.

According to my invention tensioning is effected by means of a spring gauge handpiece which is provided with a self-tightening cam vice-gripper which is adapted for grasping the fall of each string length.

In the drawing:--

Fig. 1 is a perspective view of the tensioning tool in operation;

Fig. 2 is a perspective view of the vice-gripper by which the string falls are held in the tensioning tool; and

Fig. 3 is a fragmentary view showing a minor additional feature in the pull plate.

The string tensioning tool seen in Fig. 1 is for hand operation and consists of a tubular casing 3!] housing a helical spring 3| in compression. This tubular casing is enclosed by a tubular handle 36 the back end of which is closed and the June 22, 1932, Serial No. d this application March 17,854. In Australia, New Britain July 10, 1931 forward end open. The fore end of the spring is held by a bridle 32 having a loop 33 at the back end of it and through this loop and the butt of the handle 38 is passed a rivet I60. A trace or tensioning bridle it I is connected at its back end to the inner end of the spring 3i and to the inner end of the casing 36, and at its fore end it is connected to a pull head 3'! which carries a grip vice. A slot 38 in one side of the casing 39 is graduated along the edge of it to indicate the tension on the spring; the spring is provided on its front end with a pointer past which the scale moves as the spring is flexed.

The pull head 3'! is fitted with spring separating grooved pinch jaws 42--i2 one of which is fixed and the other movable laterally. An eccentric or cam 43 having a handpiece 3 2- on it acts against the movable jaw 42 to close it against the fixed jaw 42 Forwardly of the pinch vice is a fixed bitt 45 which may have a fair lead knob 35 on its peripheral edge; this knob is not necessary, but may be provided to minimize risk of the string slipping over the bitt in the tensioning operation. ihe string fall to be tensioned is given a turn round this bitt and is then clamped in the mating grooves ll in the vice jaws by a finger movement applied to the cam lever. Tension may then be readily applied to the string by hauling on the tool, the load being read directly off the graduated scale on the side of the slot in the body member.

ii is a limit check for preventing movement of the vice cam beyond the full open position. 7! is a guide check at the fore end of the vice jaws for taking the tension load directly to the vice plate and for aligning the string in the vice jaw grooveways.

Fig. 3 shows a provision for holding short ends of strings, which will not Wind round the bitt and pass into the vice. These short ends are reeved through a hole in the pull plate and checked with a knot and are thus held while being tensioned.

What I claim as my invention and desire to secure by Letters Patent is:

A racket string tensioning tool of the dynamometer class comprising in combination a pull head, a helical spring, a tubular metal sleeve loosely encasing said spring, a tubular handle grip in which said sleeved spring is slidingly accommodated, a bridle connecting the outer end of said spring with the remote endof the handle grip, a tensioning bridle connecting both the inner end of the tubular sleeve and the inner end of said spring with said pull head, said pull head being disposed' in alinement with said spring beyond that end thereof which is bridled to the handle grip, a bitt fixed on said'pull head and adapted to carry a turn of racket string, a fixed; pinch jaw and a: movable pinch-jaw mounted on. said pull head;

and adapted to grip the fall of a racket string led from said bitt, a self-holding eccentric cam having a handle and centered on said pull head adapted for applying pressure against said movable jaw to force it towards said'fixed jaw; and

means for gauging the distortion of said spring to indicate the tension applied to a string in the stringing operation. I

JAMES BUTTON PROCTOR. 

